Abstract: All the shapes of the isothermal remanent magnetization(IRM) curves of the samples, which were derived from the heat-treated sideriteand sand siderite samples within a certain temperature range, can be divided into three types, each corresponding one essamble of the initial states of remanent magnetization. According to the existence of segmentswith minus slope for theanomalous IRM curves, a reverse magnetic phase is suggested to have occurred during the heat treatment before and the anomalous behavior of IRM curve is tentatively explained with the coupling between a normal magnetic phase and a reverse magnetic phase. Thiskind of revere remanent magnetization were obtained by magnetizing at the room temperature and no any thermal and chemical processes participate in the magnetizing. Therefore, it differs, in essence, from the thermal and chemical reverse remanent magnetization which have been observed before.

Key words: the anomalous IRM curves, reverse magnetic, phase, heat treatment

摘要： 菱铁矿经过适当温度热处理后的异常等温剩磁（IRM）曲线的全部形态与初始剩磁态的3个集合相对应。根据IRM曲线存在负微商线段这一事实，提出有逆磁相存在，并用正常磁相和逆磁相的耦合来解释这种异常等温剩磁行为。这种逆向剩磁是在室温下获得的，在磁化时没有任何热过程和化学过程发生，在本质上与已观察到的逆向热剩磁和逆向化学剩磁不同。

关键词: 异常等温剩磁曲线, 逆向磁化, 菱铁矿, 热处理